The correct statement about multicellular organisms is:
**A multicellular organism has many specialized cells.**
In multicellular organisms, cells differentiate to perform specific functions, which allows for increased complexity and efficiency in carrying out life processes. The other statements are incorrect for the following reasons:
- **Cells in multicellular organisms can reproduce by binary fission**: Generally, cells in multicellular organisms divide by mitosis or meiosis, not binary fission, which is typical of prokaryotic organisms.
- **The cells of a multicellular organism must perform all life functions**: In multicellular organisms, different types of cells perform specialized functions, so not every cell is responsible for all life functions.
- **Every cell of a multicellular organism is responsible for movement**: Movement is typically a function of specialized muscle cells, and not all cells in a multicellular organism are responsible for movement.